The invention relates to a disposable injector with a housing that contains at least one mechanical spring energy reservoir, at least one cylinder/piston unit that can be filled at least temporarily with active substance, at least one piston-actuating rod and at least one trigger unit.
An injector of this kind is known from EP 0 595 508 B1. It is constructed in such a way that the individual structural groups—namely the spring energy reservoir, cylinder/piston unit and trigger unit—cannot be separated from one another or handled separately. The trigger unit too is a complicated multi-part system.
A comparable device for injection of medicaments is also known from DE 695 06 521 T2, where the charged spring energy reservoir is secured by means of a breakable pin. When the breakable pin is broken by manual actuation, the spring that drives the syringe piston is released.
Moreover, DE 102 40 165 A1 describes a device for dosed ejection of a liquid active substance. In said device, the active substance is located in a syringe barrel. A syringe piston is spring-loaded and forced toward the active substance. The advance movement of the syringe piston is braked periodically by a band. The braking mechanism corresponds to the clock generator of a mechanical timepiece. The band is wound round the shaft of an escape wheel. The rotation of the escape wheel is triggered periodically at angles of rotation via an oscillating armature.
Therefore, the problem addressed by the present invention is that of developing a disposable injector of modular design which, with a small overall size, comprises only a small number of structural parts and, while being easy to handle, ensures reliable storage and reliable operation.